Patients with severely ischemic legs may have, in addition to low perfusion of their feet, vasoconstriction of skin vessels which renders their skin more susceptible to otherwise trivial trauma (decubitus). This peripheral vasoconstriction can often be abolished by surgical or pharmacological sympathectomy. It can also be avoided with bulky isothermic dressings which promote autonomic dilatation of skin vessels.
When lying in bed a good portion of the weight of the extremity of the patient rests on the posterior aspect of the heel. Patients with ischemic extremities are prone to develop ulcerations in this pressure point which, once established, nearly always necessitates an amputation unless an arterial reconstruction is possible.
In patients with severely ischemic legs other trivial injuries may occur with the limited ambulation which is allowed to them. A small abrasion caused by contact with the edge of the bed or chair may result in a non-healing ulceration with catastrophic results.
One protective appliance that has been used in the past consists of a cylinder of synthetic or natural cotton which is wrapped around the foot and lower leg and is held in place by a tubular elastic net. However, removal and reapplication for inspection and care is awkward and after minimal ambulation they must be discarded and replaced.
A general object of the present invention is to provide a boot which gives improved protection for the foot and lower leg of a patient who may, for example, be suffering from arterial disease.
The boot of the present invention has the following characteristics:
(1) It may be worn by patients in bed and also allows limited ambulation (to bathroom, at bedside, etc.).
(2) It protects the foot from trauma.
(3) It is isothermic and, to the extent possible, prevents heat loss from the foot, while at the same time permitting breathing and evaporation of sweat from the skin surface.
(4) It distributes the weight of the extremity over a large surface area. The design takes into consideration the fact that the weight bearing surface when the patient is lying down will not be at the bottom of the heel but rather over the heel cord and the lower aspect of the calf on a much wider area than that upon which the foot would normally rest. By transferring the weight of the extremity to a much larger area, the effective pressure insult on the skin is diminished.
(5) It is soft and will reach to the junction of the lower and middle third of the calf.
(6) Because it is intended for use by individuals who oftentimes have infection or ulcerations in the foot, the boot is designed to be disposable.
(7) It is not so costly that it cannot be discarded after use by a patient in the hospital.
(8) It allows for easy opening of the boot for inspection and care purposes.
(9) It is free of hard surfaces or corners on the outer surface to avoid injury to the other extremity of the patient since it will be used in most cases by bedridden patients.
These and other objects will become more apparent as the following description proceeds, especially when considered with the accompanying drawings.